i have the JL Audio Stealth Bof in my 05 F-150 Ext cab.It has a 10" sub and is designed to mount underneath the back seat. They are made Custom for each different year and model vehicle, and even match your interior. The 10 is downfiring, and is ported out the side. The sound of this is incredible/ I also have JL Audio 6x8 replacing the OEM speakers, and 2 Zapco amps, and A Zapco Preamp. Now I know to the purists not having seperate mids and tweets, and a manufactured box may not sound ideal, but I swear to God It's incredible. I have around 900 watts. To me JL Audio is the best speaker company out there, and Zapco has had a resurgance in the amplifier dept. For the money I spent I could not be happier.